Bachmann Ex-LMS Ivatt 4MT 2-6-0 DCC Fitting Guide

Whilst searching to fill the missing BR standard 4MT gaps in the locoyard fleet, I stumbled upon an Ivatt 4MT 2-6-0. This is not a southern engine and in that respect quite out of place in the collection, but nevertheless it is an unusual addition to the fleet and a review of it will be published some time in the near future. STOP PRESS! You may want to read the suggestion sent in at the bottom of this guide by a reader of the locoyard blog (David Turner), it sounds like an easier method!

These locomotives have the nickname “flying pig” and aptly; despite being DCC ready, Bachmann’s model proved to be somewhat of a pig when fitting a decoder! As with Bachmann’s GWR Hall class (click here for DCC fitting guide) it has a loco-mounted DCC plug with very little space for a decoder, unless you are prepared to remove weight from the model and reduce it’s haulage capabilities. There is a way around this though, as I’ll explain…

The body is separated from the chassis by removing screws as indicated above. Although I had no problems with this model, there have been many reports of pipework having being stuck to both body and chassis and breaking upon separation. Needless to say, be very careful when pulling it apart and if you need to break off piping, do it at a point that can easily be re-fixed by adhesive if necessary.

The DCC mounting socket sits in the locomotive smokebox and there is barely any extra space for a decoder. I attempted squeezing in a Hornby R8249 decoder with unneeded wires removed, but it would not fit. Removing the weight that sits in the boiler of the locomotive is an option, but traction would be ruined in this model (which incidentally isn’t amazing.) The narrow gap between the DCC socket and locomotive body means that direct plug-in decoders such as the Gaugemaster DCC24 or TCS DP2X-UK will not leave enough clearance as-is. At first I was stuck and considered removing the DCC socket and hard-wiring a DCC decoder, but then had a brain wave that meant the solder iron didn’t need to be plugged in!

Now the Gaugemaster DCC24 chip will fit in the body space but not when attached to the socket; unless you free the socket from the chassis. So, the next step involved removing the two screws that hold the DCC socket onto the chassis as indicated above and allowing the socket to move freely.

Now fit the decoder into the socket as above. As usual, test that this works, though take care with the loose DCC socket. Note – the socket is attached by wires that have some slack, which makes this operation possible.

You will now be able to coax the decoder/socket into the space and re-fit the chassis together. You’ll now have a DCC fitted model with the weight in the boiler that the model needs to run well.

Since completing the job, we’ve been contacted by David Turner who has the following suggestion:

I read your info on fitting a decoder to the oo Ivatt 4MT 2-6-0. Fortunately before I attempted this I had bought some Gaugemaster DCC 22 very small decoders with 8pin connector and I managed to fit the decoder and connector in place without resorting to surgery or a soldering iron. It was a very tight fit and took several attempts but when the body and chassis are separated you can test the decoder fits in the smokebox cavity – which it does – so I knew it had to work if I persisted – a spot of blu tack on the inside of the smokebox door to hold the decoder during assembly did the trick – the rest is down to getting the wires into the remaining space. It is now running happily on my layout.